Quantitative evaluation of carotid plaque echogenicity by integrated backscatter analysis: correlation with symptomatic history and histologic findings.
OBJECTIVE
Echogenicity of carotid plaque well reflects the risk of ischemic stroke and may be predictive of the histologic content of the plaque. However, objective evaluation of plaque echogenicity has been hampered by a lack of established quantitative measures. This study examined the relation between echogenicity assessed by integrated backscatter (IBS) analysis and (1) symptomatic history and (2) histologic features of carotid plaques.


METHODS
We used acoustic densitometry to quantify by IBS analysis the echogenicity of 31 carotid plaques of 26 patients undergoing carotid endarterectomy or stenting. IBS was subsequently compared with histologic findings of the respective tissue in 10 patients who underwent endarterectomy. The IBS value was calibrated with 2 reference structures (vessel lumen and adventitia) as the IBS index.


RESULTS
The IBS index of symptomatic plaques was lower than that of asymptomatic plaques (23.1 +/- 12.5 vs. 36.5 +/- 18.2, p < 0.05). The IBS index in fatty/necrotic atheromatous sites (n = 20, 16.6 +/- 10.7) was lower than that in fibrous (n = 26, 42.4 +/- 13.6, p < 0.01) or calcified (n = 11, 87.7 +/- 17.4, p < 0.01) sites and the same as that in intraplaque hemorrhagic sites (n = 50, 23.6 +/- 16.9).


CONCLUSIONS
Carotid plaque echogenicity, as quantitatively assessed by IBS analysis, correlates well with the presence or absence of prior symptoms and histologic contents of the plaques. IBS analysis may aid in the assessment of carotid plaque-related risk of stroke.
Nagano
Keiko
K
Stroke Division, Department of Internal Medicine, National Cardiovascular Center, Osaka, Japan. knagano@medone.med.osaka-u.ac.jp
Yamagami
Hiroshi
H
Tsukamoto
Yoshitane
Y
Nagatsuka
Kazuyuki
K
Yasaka
Masahiro
M
Nagata
Izumi
I
Hori
Masatsugu
M
Kitagawa
Kazuo
K
Naritomi
Hiroaki
H
D000368:Aged; D020757:Amaurosis Fugax / Q000209:etiology; D050197:Atherosclerosis / Q000000981:diagnostic imaging; D002545:Brain Ischemia / Q000209:etiology; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000473:pathology; D002138:Calibration; D002340:Carotid Artery Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D017536:Carotid Artery, Common / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D002343:Carotid Artery, Internal / Q000737:chemistry / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D015897:Comorbidity; D003720:Densitometry / Q000379:methods; D038524:Diffusion Magnetic Resonance Imaging; D016894:Endarterectomy, Carotid; D005260:Female; D006470:Hemorrhage / Q000209:etiology; D006801:Humans; D002546:Ischemic Attack, Transient / Q000209:etiology; D008055:Lipids / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D012307:Risk Factors; D015607:Stents; D018616:Ultrasonography, Doppler, Duplex
D008055:Lipids